Pleatco PA100 Replacement Cartridge for Hayward Star-Clear II C1100, 1 Cartridge Replacement filter for pool and spa cleaning systems 50% open ABS free flow cores maximize water flow through REEMAY filter media Antimicrobial end caps resist chlorine degradation and provide support to filter material for a longer life span 25-1/2-by-3-by-3-inches. Made in the USA NOTE - This product is for PA100 ONLY, does not fit PA100N